Growing Hydroponic Raspberries, part 1

Typically raspberries are not considered good plants to grow hydroponically by growers because they are long term plants that depending on type of raspberry plant, may not produce any fruit in the first year. Because there are no real large producers of out of season raspberry’s in the USA, most of them are imported from Mexico and Chile during the off season. That results in pour quality as well as higher prices because of the long distance they have to travel get to market. Even with the high prices and low quality of off season raspberry’s, people are still apparently willing to spend their money on them. And for those people who like fresh raspberries, growing their own can be very rewarding.

Raspberry’s are a high value crop that can sell for between $3 and $6 for a 1/2 pint during the off season, and typically sell for around $3 or more when they are in season. Each plant can produce 8 to 11 1/2 pints of berry’s in one season (about 4 months) for second year plants, and 3 or 4 year old plants can produce as much as 20 1’/2 pints or more in a season. Let say they sell at $3.50 for a 1/2 pint, and each plant yields 11, 1/2 pints, that’s a total of $38.50 (11, 1/2 pints at $4.50= $49.50) of product from each plant. So there’s a lot of potential for profit, especially when rotating plants to provide for both in and out of season berry’s. Even so very little information exists on hydroponically grow off season raspberry’s. Yet because they are a highly perishable product, there is always a demand for fresh locally grown high-quality raspberry’s.

Types of Raspberries
There are two basic types of raspberries plants (called canes). Primocane-fruiting (Fall-Bearing, and/or everbearing) and Floricane-fruiting (Summer-bearing). Primocane-fruiting, produces fruits at the top of the first year canes. If allowed to over-winter, these same canes will produce fruit again on the lower portions of the canes in early summer of the second year. However the second year fruit of the primocanes is said to be less quality than the first year fruit. Some growers will sacrifice the second-year crop in favor of the smaller but higher quality late fall primocane crops by pruning the canes to the ground, at either the end of the first years harvest or in early spring of the next year before they begin to grow again. Then new canes will continue to grow and fruit each year in late summer.

Floricane-fruiting (only produce fruit from buds on second-year canes), and unlike primocane-fruiting raspberries, these canes must stay intact through the winter and into the following growing season to fruit. Also, during second-year of floricane-fruiting raspberry plants, while the canes are flowering and fruiting new first-year canes are growing (also called primocanes because these are the first year canes). These will produce fruit in the fallowing second year. At the end of the harvest year the second year canes (floricanes) should be cut to make room for the new primocanes that will fruit the fallowing year. If not they will just die and not produce fruit anyway, taking energy away from the fruiting canes.

Advantages and Disadvantages Primocane-fruiting Advantages

long harvest season from the same plant

less labor moving plants in and out of the greenhouse because of the long season

higher density of plants can be placed in the same space

only a simple trellis is required for support

Primocane-fruiting Disadvantages

mites and other pests can build up during the longer harvest season

bees must be active thought the long season for pollination

Primocane plant yields are lower than floricane

Floricane-fruiting Advantages

superior flavor and fruit size than primocane

shorter harvest season, but with higher yields

easy to schedule plant rotations for production cycles

bees have a shorter season they need to be active

pests easier to control because of shorter growing season

Floricane-fruiting Disadvantages

larger plants so they take up more space

plants require more trellising support than primocane

plant requires more labor in manipulation of the canes

it may be two years before the full potential yields are realized

accumulation from the chilling is required to come out of dormancy

Raspberry cultivars
For some reason not all raspberry cultivars (variety of a plant) produce well in the greenhouse environment. Some of the varieties that have shown to do well in the greenhouse include: (primocane varieties) Caroline, Josephine, Autumn Bliss, Autumn Britten, (Floricane varieties) Tulameen, Chilliwack, Cascade Delight and Encore. The Tulameen variety seems to be a particular favorite for it’s large size as well as it’s flavor, and also seems to be particularly resistant to insects and disease.

Growers that want to grow raspberries for profit will want to obtain high quality virus indexed plants from a reputable source. Preferably from a nursery that sells certified virus indexed stock. Certified virus indexed raspberry stock is propagated from plants that have never been exposed to the outdoor environment. They are grown under very strict conditions in order to be free of pests and viruses, including soil born pests and pathogens. Field grown plants can be used, but are much more likely to introduce pests and disease into the greenhouse that can affect the entire crop. Also virus indexed raspberry plants generally grow more vigorously, as well as be more productive and even tend to live longer.